Currently, many types of glassware require ground and polished surfaces. Examples of such are ophthalmic lenses, optical instrument lenses, cathode ray tube faceplates, and plate glass. Grinding and polishing adds significantly to the cost of such articles not only because of the space requirements for the necessary equipment but also because of the time and energy that must be expended in carrying out the processes. Consequently, research efforts have been extensive to devise a simpler, less expensive means for preparing articles of equivalent quality.
The well-known process of acid polishing suffices in some instances but is inadequate for many purposes. Moreover, that process is a time consuming, expensive operation which frequently involves a concomitant waste disposal problem.
A further characteristic of glassware which must be given serious consideration is that of mechanical strength and, more particularly, the effect of surface defects on such strength. It is well-recognized in the art that very minute cracks tend to develop in the surface thereof as a glass article is cooled from the softened state, and that such cracks substantially diminish the inherently high strength of a defect-free, pristine glass surface. Again, an acid wash may be helpful or a chemical strengthening procedure may be applied to the article, but such practices add considerably to the manufacturing cost and are useful only in a limited range of glass compositions. Accordingly, a better solution to the problem has been sought.